Typedefs

typedef struct _Eet_Data_Descriptor Eet_Data_DescriptorOpaque handle that have information on a type members.
typedef struct _Eet_Data_Descriptor_ClassEet_Data_Descriptor_ClassInstructs Eet about memory management for different needs under serialization and parse process.

Detailed Description

While Eet core just handles binary blobs, it is often required to save some structured data of different types, such as strings, integers, lists, hashes and so on.

Eet can serialize and then parse data types given some construction instructions. These are defined in two levels:

•

Eet_Data_Descriptor_Class to tell generic memory handling, such as the size of the type, how to allocate memory, strings, lists, hashes and so on.

•

Eet_Data_Descriptor to tell inside such type, the members and their offsets inside the memory blob, their types and names. These members can be simple types or other Eet_Data_Descriptor, allowing hierarchical types to be defined.

Given that C provides no introspection, this process can be quite cumbersome, so we provide lots of macros and convenience functions to aid creating the types.

edd The data descriptor to add the type to.
struct_type The type of the struct.
name The string name to use to encode/decode this member (must be a constant global and never change).
member The struct member itself to be encoded.
subtype The type of hash member to add.

This macro lets you easily add a fixed size array of other data types. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(), with the subtype being the exception. This must be the data descriptor of the element that is in each member of the hash to be stored.

edd The data descriptor to add the type to.
struct_type The type of the struct.
name The string name to use to encode/decode this member (must be a constant global and never change).
member The struct member itself to be encoded.
type The type of the member to encode.

This macro is a convenience macro provided to add a member to the data descriptor edd. The type of the structure is provided as the struct_type parameter (for example: struct my_struct). The name parameter defines a string that will be used to uniquely name that member of the struct (it is suggested to use the struct member itself). The member parameter is the actual struct member itself (for eet_dictionary_string_check example: values), and type is the basic data type of the member which must be one of: EET_T_CHAR, EET_T_SHORT, EET_T_INT, EET_T_LONG_LONG, EET_T_FLOAT, EET_T_DOUBLE, EET_T_UCHAR, EET_T_USHORT, EET_T_UINT, EET_T_ULONG_LONG or EET_T_STRING.

edd The data descriptor to add the type to.
struct_type The type of the struct.
name The string name to use to encode/decode this member (must be a constant global and never change).
member The struct member itself to be encoded.
subtype The type of hash member to add.

This macro lets you easily add a hash of other data types. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(), with the subtype being the exception. This must be the data descriptor of the element that is in each member of the hash to be stored.

edd The data descriptor to add the type to.
struct_type The type of the struct.
name The string name to use to encode/decode this member (must be a constant global and never change).
member The struct member itself to be encoded.
subtype The type of linked list member to add.

This macro lets you easily add a linked list of other data types. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(), with the subtype being the exception. This must be the data descriptor of the element that is in each member of the linked list to be stored.

edd The data descriptor to add the type to.
struct_type The type of the struct.
name The string name to use to encode/decode this member (must be a constant global and never change).
member The struct member itself to be encoded.
subtype The type of sub-type struct to add.

This macro lets you easily add a sub-type (a struct that's pointed to by this one). All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(), with the subtype being the exception. This must be the data descriptor of the struct that is pointed to by this element.

edd The data descriptor to add the type to.
struct_type The type of the struct.
name The string name to use to encode/decode this member (must be a constant global and never change).
member The struct member itself to be encoded.
type_member The member that give hints on what is in the union.
unified_type Describe all possible type the union could handle.

This macro lets you easily add an union with a member that specify what is inside. The unified_type is an Eet_Data_Descriptor, but only the entry that match the name returned by type_get will be used for each serialized data. The type_get and type_set callback of unified_type should be defined.

edd The data descriptor to add the type to.
struct_type The type of the struct.
name The string name to use to encode/decode this member (must be a constant global and never change).
member The struct member itself to be encoded.
subtype The type of hash member to add.

This macro lets you easily add a fixed size array of other data types. All the parameters are the same as for EET_DATA_DESCRIPTOR_ADD_BASIC(), with the subtype being the exception. This must be the data descriptor of the element that is in each member of the hash to be stored.

edd The data descriptor to add the type to.
struct_type The type of the struct.
name The string name to use to encode/decode this member (must be a constant global and never change).
member The struct member itself to be encoded.
type_member The member that give hints on what is in the union.
unified_type Describe all possible type the union could handle.

This macro lets you easily define what the content of member points to depending of the content of type_member. The type_get and type_set callback of unified_type should be defined. If the the type is not know at the time of restoring it, eet will still call type_set of unified_type but the pointer will be set to a serialized binary representation of what eet know. This make it possible, to save this pointer again by just returning the string given previously and telling it by setting unknow to EINA_TRUE.

Since:

1.2.4

See also:

Eet_Data_Descriptor_Class

#define EET_DATA_DESCRIPTOR_CLASS_VERSION 3

The version of Eet_Data_Descriptor_Class at the time of the distribution of the sources. One should define this to its version member so it is compatible with abi changes, or at least will not crash with them.

This macro is an helper that set all the parameter of an Eet_Data_Descriptor_Class correctly when you use Eina data type with stream. Parameters:

Clas The Eet_Data_Descriptor_Class you want to set.
Type The type of the structure described by this class.

Returns:

EINA_TRUE if the structure was correctly set (The only reason that could make it fail is if you did give wrong parameter).

Since:

1.2.3

#define EET_I_LIMIT 128

Other type exist but are reserved for internal purpose.

Typedef Documentation

Eet_Data_Descriptor

Opaque handle that have information on a type members. The members are added by means of EET_DATA_DESCRIPTOR_ADD_BASIC(), EET_DATA_DESCRIPTOR_ADD_SUB(), EET_DATA_DESCRIPTOR_ADD_LIST(), EET_DATA_DESCRIPTOR_ADD_HASH() or eet_data_descriptor_element_add().

Function Documentation

Decode a data structure from an arbitary location in memory. Parameters:

edd The data descriptor to use when decoding.
data_in The pointer to the data to decode into a struct.
size_in The size of the data pointed to in bytes.

Returns:

NULL on failure, or a valid decoded struct pointer on success.

This function will decode a data structure that has been encoded using eet_data_descriptor_encode(), and return a data structure with all its elements filled out, if successful, or NULL on failure.

The data to be decoded is stored at the memory pointed to by data_in, and is described by the descriptor pointed to by edd. The data size is passed in as the value to size_in, ande must be greater than 0 to succeed.

This function is useful for decoding data structures delivered to the application by means other than an eet file, such as an IPC or socket connection, raw files, shared memory etc.

This function is an internal used by macros. This function is used by macros EET_DATA_DESCRIPTOR_ADD_BASIC(), EET_DATA_DESCRIPTOR_ADD_SUB() and EET_DATA_DESCRIPTOR_ADD_LIST(). It is complex to use by hand and should be left to be used by the macros, and thus is not documented.

Parameters:

edd The data descriptor handle to add element (member).
name The name of element to be serialized.
type The type of element to be serialized, like EET_T_INT. If EET_T_UNKNOW, then it is considered to be a group, list or hash.
group_type If element type is EET_T_UNKNOW, then the group_type will speficy if it is a list (EET_G_LIST), array (EET_G_ARRAY) and so on. If EET_G_UNKNOWN, then the member is a subtype (pointer to another type defined by another Eet_Data_Descriptor).
offset byte offset inside the source memory to be serialized.
count number of elements (if EET_G_ARRAY or EET_G_VAR_ARRAY).
counter_name variable that defines the name of number of elements.
subtype If contains a subtype, then its data descriptor.

Encode a dsata struct to memory and return that encoded data. Parameters:

edd The data descriptor to use when encoding.
data_in The pointer to the struct to encode into data.
size_ret pointer to the an int to be filled with the decoded size.

Returns:

NULL on failure, or a valid encoded data chunk on success.

This function takes a data structutre in memory and encodes it into a serialised chunk of data that can be decoded again by eet_data_descriptor_decode(). This is useful for being able to transmit data structures across sockets, pipes, IPC or shared file mechanisms, without having to worry about memory space, machine type, endianess etc.

The parameter edd must point to a valid data descriptor, and data_in must point to the right data structure to encode. If not, the encoding may fail.

On success a non NULL valid pointer is returned and what size_ret points to is set to the size of this decoded data, in bytes. When the encoded data is no longer needed, call free() on it. On failure NULL is returned and what size_ret points to is set to 0.

This function creates a new data descriptore and returns a handle to the new data descriptor. On creation it will be empty, containing no contents describing anything other than the shell of the data structure.

Parameters:

eddc The data descriptor to free.

You add structure members to the data descriptor using the macros EET_DATA_DESCRIPTOR_ADD_BASIC(), EET_DATA_DESCRIPTOR_ADD_SUB() and EET_DATA_DESCRIPTOR_ADD_LIST(), depending on what type of member you are adding to the description.

Once you have described all the members of a struct you want loaded, or saved eet can load and save those members for you, encode them into endian-independant serialised data chunks for transmission across a a network or more.

This function use str_direct_alloc and str_direct_free. It is usefull when the eet_data you are reading come from a file and have a dictionnary. This will reduce memory use, improve the possibility for the OS to page this string out. But be carrefull all EET_T_STRING are pointer to a mmapped area and it will point to nowhere if you close the file. So as long as you use this strings, you need to have the Eet_File open.

Since:

1.2.3

EAPI void eet_data_descriptor_free (Eet_Data_Descriptor * edd)

This function frees a data descriptor when it is not needed anymore. Parameters:

edd The data descriptor to free.

This function takes a data descriptor handle as a parameter and frees all data allocated for the data descriptor and the handle itself. After this call the descriptor is no longer valid.

name The string name of this data structure (most be a global constant and never change).
size The size of the struct (in bytes).
func_list_next The function to get the next list node.
func_list_append The function to append a member to a list.
func_list_data The function to get the data from a list node.
func_list_free The function to free an entire linked list.
func_hash_foreach The function to iterate through all hash table entries.
func_hash_add The function to add a member to a hash table.
func_hash_free The function to free an entire hash table.

Returns:

A new empty data descriptor.

This function creates a new data descriptore and returns a handle to the new data descriptor. On creation it will be empty, containing no contents describing anything other than the shell of the data structure.

You add structure members to the data descriptor using the macros EET_DATA_DESCRIPTOR_ADD_BASIC(), EET_DATA_DESCRIPTOR_ADD_SUB() and EET_DATA_DESCRIPTOR_ADD_LIST(), depending on what type of member you are adding to the description.

Once you have described all the members of a struct you want loaded, or saved eet can load and save those members for you, encode them into endian-independant serialised data chunks for transmission across a a network or more.

The function pointers to the list and hash table functions are only needed if you use those data types, else you can pass NULL instead.

Since:

1.0.0

Deprecated

use eet_data_descriptor_stream_new() or eet_data_descriptor_file_new()

This function creates a new data descriptore and returns a handle to the new data descriptor. On creation it will be empty, containing no contents describing anything other than the shell of the data structure.

Parameters:

eddc The data descriptor to free.

You add structure members to the data descriptor using the macros EET_DATA_DESCRIPTOR_ADD_BASIC(), EET_DATA_DESCRIPTOR_ADD_SUB() and EET_DATA_DESCRIPTOR_ADD_LIST(), depending on what type of member you are adding to the description.

Once you have described all the members of a struct you want loaded, or saved eet can load and save those members for you, encode them into endian-independant serialised data chunks for transmission across a a network or more.

This function specially ignore str_direct_alloc and str_direct_free. It is usefull when the eet_data you are reading don't have a dictionnary like network stream or ipc. It also mean that all string will be allocated and duplicated in memory.

ef A valid eet file handle.
name Name of the entry. eg: '/base/file_i_want'.
dumpfunc The function to call passed a string when new data is converted to text
dumpdata The data to pass to the dumpfunc callback.

Returns:

1 on success, 0 on failure

This function will take an open and valid eet file from eet_open() request the data encoded by eet_data_descriptor_encode() corresponding to the key name and convert it into human readable ascii text. It does this by calling the dumpfunc callback for all new text that is generated. This callback should append to any existing text buffer and will be passed the pointer dumpdata as a parameter as well as a string with new text to be appended.

ef The eet file handle to read from.
edd The data descriptor handle to use when decoding.
name The key the data is stored under in the eet file.

Returns:

A pointer to the decoded data structure.

This function decodes a data structure stored in an eet file, returning a pointer to it if it decoded successfully, or NULL on failure. This can save a programmer dozens of hours of work in writing configuration file parsing and writing code, as eet does all that work for the program and presents a program-friendly data structure, just as the programmer likes. Eet can handle members being added or deleted from the data in storage and safely zero-fills unfilled members if they were not found in the data. It checks sizes and headers whenever it reads data, allowing the programmer to not worry about corrupt data.

Once a data structure has been described by the programmer with the fields they wish to save or load, storing or retrieving a data structure from an eet file, or from a chunk of memory is as simple as a single function call.

data_in The pointer to the data to decode into a struct.
size_in The size of the data pointed to in bytes.
dumpfunc The function to call passed a string when new data is converted to text
dumpdata The data to pass to the dumpfunc callback.

Returns:

1 on success, 0 on failure

This function will take a chunk of data encoded by eet_data_descriptor_encode() and convert it into human readable ascii text. It does this by calling the dumpfunc callback for all new text that is generated. This callback should append to any existing text buffer and will be passed the pointer dumpdata as a parameter as well as a string with new text to be appended.

Take an ascii encoding from eet_data_text_dump() and re-encode in binary. Parameters:

text The pointer to the string data to parse and encode.
textlen The size of the string in bytes (not including 0 byte terminator).
size_ret This gets filled in with the encoded data blob size in bytes.

Returns:

The encoded data on success, NULL on failure.

This function will parse the string pointed to by text and return an encoded data lump the same way eet_data_descriptor_encode() takes an in-memory data struct and encodes into a binary blob. text is a normal C string.

Write a data structure from memory and store in an eet file. Parameters:

ef The eet file handle to write to.
edd The data descriptor to use when encoding.
name The key to store the data under in the eet file.
data A pointer to the data structure to ssave and encode.
compress Compression flags for storage.

Returns:

bytes written on successful write, 0 on failure.

This function is the reverse of eet_data_read(), saving a data structure to an eet file.